<s>
A	O
homopolar	B-Algorithm
generator	I-Algorithm
is	O
a	O
DC	O
electrical	O
generator	O
comprising	O
an	O
electrically	O
conductive	O
disc	O
or	O
cylinder	O
rotating	O
in	O
a	O
plane	O
perpendicular	O
to	O
a	O
uniform	O
static	O
magnetic	O
field	O
.	O
</s>
<s>
It	O
is	O
also	O
known	O
as	O
a	O
unipolar	B-Algorithm
generator	I-Algorithm
,	O
acyclic	B-Algorithm
generator	I-Algorithm
,	O
disk	B-Algorithm
dynamo	I-Algorithm
,	O
or	O
Faraday	B-Algorithm
disc	I-Algorithm
.	O
</s>
<s>
They	O
are	O
unusual	O
in	O
that	O
they	O
can	O
source	O
tremendous	O
electric	O
current	O
,	O
some	O
more	O
than	O
a	O
million	O
amperes	B-General_Concept
,	O
because	O
the	O
homopolar	B-Algorithm
generator	I-Algorithm
can	O
be	O
made	O
to	O
have	O
very	O
low	O
internal	O
resistance	O
.	O
</s>
<s>
Also	O
,	O
the	O
homopolar	B-Algorithm
generator	I-Algorithm
is	O
unique	O
in	O
that	O
no	O
other	O
rotary	O
electric	O
machine	O
can	O
produce	O
DC	O
without	O
using	O
rectifiers	O
or	O
commutators	O
.	O
</s>
<s>
The	O
first	O
homopolar	B-Algorithm
generator	I-Algorithm
was	O
developed	O
by	O
Michael	O
Faraday	O
during	O
his	O
experiments	O
in	O
1831	O
.	O
</s>
<s>
It	O
is	O
frequently	O
called	O
the	O
Faraday	B-Algorithm
disc	I-Algorithm
or	O
Faraday	O
wheel	O
in	O
his	O
honor	O
.	O
</s>
<s>
It	O
was	O
the	O
beginning	O
of	O
modern	O
dynamos	B-Language
that	O
is	O
,	O
electrical	O
generators	O
which	O
operate	O
using	O
a	O
magnetic	O
field	O
.	O
</s>
<s>
It	O
was	O
very	O
inefficient	O
and	O
was	O
not	O
used	O
as	O
a	O
practical	O
power	O
source	O
,	O
but	O
it	O
showed	O
the	O
possibility	O
of	O
generating	O
electric	O
power	O
using	O
magnetism	O
,	O
and	O
led	O
the	O
way	O
for	O
commutated	O
direct	O
current	O
dynamos	B-Language
and	O
then	O
alternating	O
current	O
alternators	O
.	O
</s>
<s>
The	O
Faraday	B-Algorithm
disc	I-Algorithm
was	O
primarily	O
inefficient	O
due	O
to	O
counterflows	O
of	O
current	O
.	O
</s>
<s>
Later	O
homopolar	B-Algorithm
generators	I-Algorithm
would	O
solve	O
this	O
problem	O
by	O
using	O
an	O
array	O
of	O
magnets	O
arranged	O
around	O
the	O
disc	O
perimeter	O
to	O
maintain	O
a	O
steady	O
field	O
around	O
the	O
circumference	O
,	O
and	O
eliminate	O
areas	O
where	O
counterflow	O
could	O
occur	O
.	O
</s>
<s>
Long	O
after	O
the	O
original	O
Faraday	B-Algorithm
disc	I-Algorithm
had	O
been	O
abandoned	O
as	O
a	O
practical	O
generator	O
,	O
a	O
modified	O
version	O
combining	O
the	O
magnet	O
and	O
disc	O
in	O
a	O
single	O
rotating	O
part	O
(	O
the	O
rotor	O
)	O
was	O
developed	O
.	O
</s>
<s>
Sometimes	O
the	O
name	O
homopolar	B-Algorithm
generator	I-Algorithm
is	O
reserved	O
for	O
this	O
configuration	O
.	O
</s>
<s>
One	O
of	O
the	O
earliest	O
patents	O
on	O
the	O
general	O
type	O
of	O
homopolar	B-Algorithm
generators	I-Algorithm
was	O
attained	O
by	O
A	O
.	O
F	O
.	O
Delafield	O
,	O
.	O
</s>
<s>
Other	O
early	O
patents	O
for	O
homopolar	B-Algorithm
generators	I-Algorithm
were	O
awarded	O
to	O
S	O
.	O
Z	O
.	O
</s>
<s>
Nikola	O
Tesla	O
was	O
interested	O
in	O
the	O
Faraday	B-Algorithm
disc	I-Algorithm
and	O
conducted	O
work	O
with	O
homopolar	B-Algorithm
generators	I-Algorithm
,	O
and	O
eventually	O
patented	O
an	O
improved	O
version	O
of	O
the	O
device	O
in	O
.	O
</s>
<s>
Tesla	O
's	O
"	O
Dynamo	B-Language
Electric	O
Machine	O
"	O
patent	O
describes	O
an	O
arrangement	O
of	O
two	O
parallel	O
discs	O
with	O
separate	O
,	O
parallel	O
shafts	O
,	O
joined	O
like	O
pulleys	O
by	O
a	O
metallic	O
belt	O
.	O
</s>
<s>
Later	O
,	O
patents	O
were	O
awarded	O
to	O
C	O
.	O
P	O
.	O
Steinmetz	O
and	O
E	O
.	O
Thomson	O
for	O
their	O
work	O
with	O
homopolar	B-Algorithm
generators	I-Algorithm
.	O
</s>
<s>
The	O
Forbes	O
dynamo	B-Language
,	O
developed	O
by	O
the	O
Scottish	O
electrical	O
engineer	O
George	O
Forbes	O
,	O
was	O
in	O
widespread	O
use	O
during	O
the	O
beginning	O
of	O
the	O
20th	O
century	O
.	O
</s>
<s>
Much	O
of	O
the	O
development	O
done	O
in	O
homopolar	B-Algorithm
generators	I-Algorithm
was	O
patented	O
by	O
J	O
.	O
E	O
.	O
Noeggerath	O
and	O
R	O
.	O
Eickemeyer	O
.	O
</s>
<s>
Homopolar	B-Algorithm
generators	I-Algorithm
underwent	O
a	O
renaissance	O
in	O
the	O
1950s	O
as	O
a	O
source	O
of	O
pulsed	O
power	O
storage	O
.	O
</s>
<s>
Some	O
of	O
these	O
losses	O
can	O
be	O
reduced	O
by	O
using	O
mercury	O
or	O
other	O
easily	O
liquefied	O
metal	O
or	O
alloy	O
(	O
gallium	O
,	O
NaK	B-Protocol
)	O
as	O
the	O
"	O
brush	O
"	O
,	O
to	O
provide	O
essentially	O
uninterrupted	O
electrical	O
contact	O
.	O
</s>
<s>
A	O
recent	O
suggested	O
modification	O
is	O
to	O
use	O
a	O
plasma	O
contact	O
supplied	O
by	O
a	O
negative	O
resistance	O
neon	B-Application
streamer	O
touching	O
the	O
edge	O
of	O
the	O
disk	O
or	O
drum	O
,	O
using	O
specialized	O
low	O
work	O
function	O
carbon	O
in	O
vertical	O
strips	O
.	O
</s>
<s>
A	O
drum-type	O
homopolar	B-Algorithm
generator	I-Algorithm
has	O
a	O
magnetic	O
field	O
(	O
B	O
)	O
that	O
radiates	O
radially	O
from	O
the	O
center	O
of	O
the	O
drum	O
and	O
induces	O
voltage	O
(	O
V	O
)	O
down	O
the	O
length	O
of	O
the	O
drum	O
.	O
</s>
<s>
Unipolar	O
inductors	O
have	O
been	O
associated	O
with	O
the	O
aurorae	O
on	O
Uranus	O
,	O
binary	O
stars	O
,	O
black	B-Application
holes	I-Application
,	O
galaxies	B-Application
,	O
the	O
Jupiter	O
Io	O
system	O
,	O
the	O
Moon	O
,	O
the	O
Solar	O
Wind	O
,	O
<	O
ref>Srnka	O
,	O
L	O
.	O
J.	O
,	O
""	O
(	O
1975	O
)	O
Astrophysics	O
and	O
Space	O
Science	O
 '	O
,	O
vol	O
.	O
</s>
<s>
177	O
–	O
204.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx1	O
sunspots	B-Application
,	O
Yang	O
,	O
Hai-Shou	O
,	O
"	O
A	O
force	O
–	O
free	O
field	O
theory	O
of	O
solar	O
flares	O
I	O
.	O
Unipolar	O
sunspots	B-Application
"	O
Chinese	O
Astronomy	O
and	O
Astrophysics	O
,	O
Volume	O
5	O
,	O
Issue	O
1	O
,	O
pp	O
.	O
</s>
<s>
77	O
–	O
83.Osherovich	O
,	O
V	O
.	O
A.	O
;	O
Garcia	O
,	O
H	O
.	O
A.	O
,	O
"	O
Electric	O
current	O
in	O
a	O
unipolar	O
sunspot	B-Application
with	O
an	O
untwisted	O
field	O
"	O
(	O
1990	O
)	O
Geophysical	O
Research	O
Letters	O
(	O
ISSN	O
0094-8276	O
)	O
,	O
vol	O
.	O
</s>
<s>
and	O
in	O
the	O
Venusian	O
magnetic	O
tail.Eroshenko	O
,	O
E	O
.	O
G.	O
,	O
"	O
Unipolar	B-Algorithm
induction	I-Algorithm
effects	O
in	O
the	O
Venusian	B-Application
magnetic	I-Application
tail	I-Application
"	O
(	O
1979	O
)	O
Kosmicheskie	O
Issledovaniia	O
,	O
vol	O
.	O
</s>
<s>
thumb|Working	O
principle	O
of	O
a	O
homopolar	B-Algorithm
generator	I-Algorithm
:	O
due	O
to	O
Lorentz	O
force	O
FL	O
negative	O
charges	O
are	O
driven	O
towards	O
center	O
of	O
the	O
rotating	O
disk	O
,	O
so	O
that	O
a	O
voltage	O
shows	O
up	O
between	O
its	O
center	O
and	O
its	O
rim	O
,	O
with	O
the	O
negative	O
pole	O
at	O
the	O
center	O
.	O
</s>
<s>
Like	O
all	O
dynamos	B-Language
,	O
the	O
Faraday	B-Algorithm
disc	I-Algorithm
converts	O
kinetic	O
energy	O
to	O
electrical	O
energy	O
.	O
</s>
<s>
Although	O
the	O
integrand	O
of	O
the	O
line	O
integral	O
is	O
time-independent	O
,	O
because	O
the	O
Faraday	B-Algorithm
disc	I-Algorithm
that	O
forms	O
part	O
of	O
the	O
boundary	O
of	O
line	O
integral	O
is	O
moving	O
,	O
the	O
full-time	O
derivative	O
is	O
non-zero	O
and	O
returns	O
the	O
correct	O
value	O
for	O
calculating	O
the	O
electromotive	O
force	O
.	O
</s>
<s>
Arthur	O
I	O
.	O
Miller	O
,	O
"	O
Unipolar	B-Algorithm
Induction	I-Algorithm
:	O
A	O
Case	O
Study	O
of	O
the	O
Interaction	O
between	O
Science	O
and	O
Technology	O
,	O
"	O
Annals	O
of	O
Science	O
,	O
Volume	O
38	O
,	O
pp	O
.	O
</s>
<s>
Olivier	O
Darrigol	O
,	O
Electrodynamics	O
from	O
Ampere	B-General_Concept
to	O
Einstein	O
,	O
Oxford	O
University	O
Press	O
,	O
2000	O
,	O
</s>
<s>
Thomas	O
Valone	O
,	O
The	O
Homopolar	O
Handbook	O
:	O
A	O
Definitive	O
Guide	O
to	O
Faraday	B-Algorithm
Disk	I-Algorithm
and	O
N-Machine	O
Technologies	O
.	O
</s>
<s>
Richard	O
A	O
.	O
Marshall	O
and	O
William	O
F	O
.	O
Weldon	O
,	O
"	O
Parameter	O
Selection	O
for	O
Homopolar	B-Algorithm
Generators	I-Algorithm
Used	O
as	O
Pulsed	O
Energy	O
Stores	O
"	O
,	O
Center	O
for	O
Electromechanics	O
,	O
University	O
of	O
Texas	O
,	O
Austin	O
,	O
Jul	O
.	O
</s>
<s>
Popular	O
Science	O
Monthly	O
,	O
Construction	O
of	O
Unipolar	O
Dynamos	B-Language
,	O
April	O
1916	O
,	O
pp	O
.	O
</s>
